TWI650247B - Sanitary pottery with photocatalyst layer - Google Patents

Abstract

An object of the present invention is to provide a sanitary ware having a photocatalyst layer excellent in durability even when exposed to an environment of acid and alkali alternately. As a solution, in order to provide a sanitary pottery including a glaze layer, an intermediate layer provided on the glaze layer, and a photocatalyst layer provided on the intermediate layer, the photocatalyst layer includes titanium oxide and oxide. Zirconium, and the intermediate layer contains 98% by mass to 85% by mass, and 2% by mass to 15% by mass of silicon dioxide, and titanium oxide and / or zirconia, thereby greatly improving the durability of the photocatalyst layer. In particular, it has durability even when repeatedly washed under conditions of different liquidity between acid and alkali.

Description

Sanitary pottery with photocatalyst layer

The present invention relates to a sanitary ware with a photocatalyst layer having excellent durability. More specifically, the present invention relates to a photocatalyst layer having a durability even with repeated cleaning under the condition that the so-called acid and alkali have different liquidity. Sanitary crockery.

A photocatalyst layer is provided on the surface of the glaze layer of the base material having the glaze layer, and a functional member utilizing the photocatalytic decomposition activity or hydrophilic activity is used in various applications. For example, sanitary ware is known in which a photocatalyst surface layer is formed on the surface of sanitary ware. Such a sanitary ware can irradiate light on its photocatalyst layer, preferably ultraviolet rays, to suppress the adhesion of dirt by exerting its hydrophilicity, and also to suppress the reproduction of bacteria by the decomposition effect of the photocatalyst. This reduces the burden of cleaning.

As such a photocatalyst layer provided on the surface of the glaze layer, a layer containing titanium oxide and a zirconium compound can be proposed to maintain good photocatalytic activity while maintaining good film strength, water resistance, or abrasion resistance (Japanese special Japanese Unexamined Patent Publication No. 2012-206907 (Patent Document 1) and Japanese Unexamined Patent Publication No. 2014-69098 (Patent Document 2)).

Although the presence of the photocatalyst layer reduces the cleaning burden, sanitary ware is regularly cleaned. At this time, acidic or alkaline liquid detergents are usually used. In addition, a brush or the like is used to remove dirt to apply physical properties. external force. What is required for the photocatalyst layer is performance that can withstand the load during such cleaning for a long period of time, and in particular, performance that does not lose photocatalytic activity and does not peel off.

On the other hand, it is known that in order to form a strong photocatalyst film, firing at a high temperature of 500 to 1000 ° C. is generally required. However, at such a high temperature, alkaline ions in the glaze of sanitary ceramics diffuse, thereby reducing the photocatalytic activity. As a countermeasure, it is known to provide an intermediate layer that suppresses the diffusion of alkaline ions with silicon dioxide as a main component between the substrate and the photocatalyst layer (for example, Japanese Patent Application Laid-Open No. 10-235201 (Patent Document 3), Japanese Patent Application Laid-Open No. 11-228865 (Patent Document 4), Japanese Patent Application Laid-Open No. 2001-152051 (Patent Document 5), and Japanese Patent Application Laid-Open No. 2003-277056 (Patent Document 6)). However, these intermediate layers are substances whose main purpose is to prevent the diffusion of alkaline ions. In addition, according to experiments conducted by the present inventors, the durability of photocatalyst layers containing titanium oxide and zirconium compounds is inferior to that of the present invention.

[Prior Art Literature] [Patent Literature]

Patent Document 1 Japanese Patent Application Publication No. 2012-206907

Patent Document 2 Japanese Patent Application Publication No. 2014-69098

Patent Document 3 Japanese Patent Application Laid-Open No. 10-235201

Patent Document 4 Japanese Patent Application Laid-Open No. 11-228865

Patent Document 5 Japanese Patent Laid-Open No. 2001-152051

Patent Document 6 Japanese Patent Laid-Open No. 2003-277056

As for the evaluation of the durability of the photocatalyst layer, a test of the photocatalyst layer after being exposed to an acidic liquid alone or to being exposed to an alkaline liquid alone has been generally performed until now. Furthermore, as long as it maintains good photocatalytic activity or is difficult to peel off even after being separately exposed to acidic or alkaline liquidity, it is evaluated as having good durability. However, according to the findings obtained by the inventors this time, in an actual use environment, for example, an acidic liquid cleaning liquid is used for cleaning, and then an alkaline liquid cleaning liquid is used for cleaning. In this case, the durability of the photocatalyst layer proposed conventionally may be insufficient.

This time, the present inventors have found that when a photocatalyst layer containing titanium oxide and zirconia is provided on the glaze layer, silicon dioxide is used as a main component, and titanium oxide and / or A layer containing zirconia in a specific ratio can greatly improve the durability of the photocatalyst layer. In particular, it was found that excellent durability is exhibited even in the case where cleaning is repeatedly performed such as alternating exposure to acid and alkali. The present invention is based on related findings.

Therefore, an object of the present invention is to provide a sanitary ware having a photocatalyst layer which is excellent in durability. In particular, an object of the present invention is to provide an excellent durability even when exposed to an environment of acid and alkali alternately. Sanitary pottery with photocatalyst layer.

In addition, the sanitary pottery of the present invention includes a glaze layer, an intermediate layer provided on the glaze layer, and a sanitary pottery provided with a photocatalyst layer provided on the intermediate layer, wherein the photocatalyst layer includes titanium oxide and oxide. Zirconium, with a titanium oxide content of 95% to 75% by mass, a zirconia content of 5 to 25% by mass, the aforementioned intermediate layer contains silicon dioxide, and titanium oxide and / or zirconia, and the silicon dioxide content is 98% % To 85% by mass, and when both titanium oxide and zirconia are included, the total content of titanium oxide and zirconia is 2% to 15% by mass.

[Best Mode for Carrying Out the Invention] definition

In the present invention, "sanitary crockery" refers to the crockery products used around the toilet and the washstand, and specifically means a toilet bowl, a urinal, a drainage hole of a toilet bowl, a toilet water tank, a washbasin for a washbasin, a handwasher and the like. In addition, "ceramics" means pottery that has been densified in ceramics to a degree that is slightly water-absorptive and has a glaze applied to its surface.

In the present invention, the "durability" of the photocatalyst layer is used as a term that indicates that the photocatalyst layer is difficult to peel off and has little deterioration with time in the photocatalyst activity, and it is particularly used as a term that indicates that the photocatalyst layer is alternately or collectively exposed to acid. In the case of liquidity with an alkali, a term in which the photocatalyst layer is difficult to peel off or there is little deterioration in photocatalytic activity is used.

Acidity means from weak acidity to strong acidity, specifically Taste is in the range of pH 5 or less, and alkaline means from weak alkaline to strong alkaline, and specifically means in the range of pH 8 or higher.

Sanitary crockery of the present invention

The sanitary pottery of the present invention has a basic structure including a base, an enamel layer on the surface, an intermediate layer provided on the enamel layer, and a photocatalyst layer provided on the intermediate layer. The intermediate layer and the photocatalyst layer are each composed of a specific composition described later.

The sanitary ware photocatalyst layer of the present invention is excellent in durability. In particular, the photocatalyst layer exhibits excellent durability even when alternately exposed to environments such as acid and alkali. As described above, the evaluation of the durability of the photocatalyst layer has so far generally been performed on a photocatalyst layer after being exposed to an acidic liquid alone or after being exposed to an alkaline liquid alone. However, even conventional photocatalyst layers that have been shown to have sufficient durability by separate evaluation with acids or bases can be observed in photocatalysts in unexpected short periods of time if exposed to an environment such as acid and alkali alternately. Delamination or degradation of photocatalytic activity. The present invention provides a sanitary ware having a photocatalyst layer that can exhibit improved durability even when exposed to such an environment that is alternately exposed to acids and alkalis.

Without wishing to be limited to a specific theory, the reason why the photocatalyst layer of the sanitary ware of the present invention is excellent is as follows. That is, the photocatalyst layer containing titanium oxide and zirconia has extremely small water permeability, and water will reach the surface of the glaze layer of sanitary ware from this. When the liquidity of the water is alternately changed between acidic and alkaline, the following reactions are promoted. First, by Acidic water causes the metal elements such as potassium, calcium, magnesium, and zinc in the glaze to dissolve. When the alkaline water reaches the elution point, the silicon-silicon bonds near it are cut off. This repetition causes the bonding between the glaze layer and the photocatalyst layer to weaken, and in the worst case, the photocatalyst layer peels off. It is considered that the intermediate layer of the present invention can strongly bond the surface of the glaze to the photocatalyst layer while preventing the infiltration of the small amount of water. The above description is only hypothetical, and the present invention is not limited thereto.

Photocatalyst layer

The photocatalyst layer of the sanitary ware of the present invention contains titanium oxide and zirconia in an amount of 95 to 75% by mass and 5 to 25% by mass, respectively. A preferable lower limit of the content of titanium oxide is 80% by mass, and a preferable upper limit thereof is 90% by mass. The preferable lower limit of the content of zirconia is 10% by mass, and the preferable upper limit thereof is 20% by mass.

In the present invention, the titanium oxide is not particularly limited as long as it is a material having photocatalytic activity. Any one of anatase type and rutile type may be used, and anatase type is preferred.

In the present invention, the film thickness of the photocatalyst layer may be appropriately determined in consideration of the required photocatalyst activity, and other various characteristics are preferred. The thickness is preferably about 50 nm to 150 nm, and the more preferable upper limit is 120 nm.

middle layer

In the sanitary pottery of the present invention, the intermediate layer is disposed between the glaze layer and the photocatalyst layer of the sanitary pottery, and includes silicon dioxide, titanium oxide, and / or zirconia. The content of silicon dioxide is in the range of 98% by mass to 85% by mass. The preferable upper limit is 95% by mass, and the preferable lower limit is 90% by mass. In addition, when the content of titanium oxide and zirconia includes both of them, the total content is in the range of 2% to 15% by mass, and the preferred upper limit is 10% by mass and the preferred lower limit is 5% by mass.

In the present invention, the film thickness of the intermediate layer can be appropriately determined within the range of improving the durability of the photocatalyst layer, but it is preferably about 50 nm to 150 nm, and a more preferable upper limit is 120 nm.

Sanitary pottery Sanitary Pottery Plain

The pottery plain of the sanitary pottery of the present invention is not particularly limited, and may be a general pottery plain of sanitary ware. In addition, a glaze layer to be an intermediate layer may be provided below the glaze layer having the above-mentioned surface properties in the outermost layer.

Production method

The sanitary ware of the present invention can be preferably produced by the following method. That is, first, a sanitary pottery raw mud slurry prepared from a ceramic pottery raw material using silica sand, feldspar, clay, etc. as a raw material is melt-molded using a water-absorptive mold to form a suitable shape. After that, the above-mentioned glaze raw material is coated on the surface of the dried molded body by appropriately selecting a general method such as spray coating, dip coating, spin coating, and roll coating. Then, the molded body formed by the precursor layer of the obtained surface glaze layer is fired. The firing temperature is preferably a temperature of 1,000 ° C. or more and 1,300 ° C. or less that sinters the ceramic green body and softens the glaze.

Glaze

The composition of the glaze that forms the glaze layer of the sanitary pottery of the present invention is not limited as long as it can achieve the aforementioned surface properties. In the present invention, the glaze raw material is generally defined as a mixture of natural mineral particles such as silica sand, feldspar, limestone, and the like. The pigment refers to, for example, a cobalt compound, an iron compound, and the like, and the opacifier refers to, for example, zirconium silicate, tin oxide, and the like. An amorphous glaze is a glaze that is made by melting a glaze raw material composed of a mixture of natural mineral particles and the like at a high temperature and then quenching and vitrifying the glaze. For example, a frit glaze can be suitably used.

According to a preferred mode of the present invention, the preferred glaze composition is, for example, 10 wt% to 30 wt% of feldspar, 15 wt% to 40 wt% of silica sand, 10 wt% to 25 wt% of calcium carbonate, and 10 wt% of corundum, talc, dolomite, and zinc oxide, respectively. % Or less, a total of 15 wt% or less of an opacifier and a pigment.

Manufacturing method of sanitary pottery of the present invention

The sanitary pottery of the present invention is manufactured by forming an intermediate layer on the glaze layer of the sanitary pottery and then forming a photocatalyst layer. Basically, the intermediate layer and the photocatalyst layer are fired on the glaze layer with silicon dioxide, and titanium oxide and / or zirconia, or their precursors, and in addition, the intermediate layer and titanium oxide and zirconia are fired on the intermediate layer. Precursors. Here, the firing for the formation of the intermediate layer and the photocatalyst layer may be performed in stages, or may be formed simultaneously. According to a preferred aspect of the present invention, the intermediate layer and the photocatalyst layer are formed by applying a coating liquid containing the above-mentioned components prepared in advance, and then firing.

According to one aspect of the present invention, a photocatalyst layer can be applied to a package. The coating liquid containing titanium oxide, zirconia, or a precursor thereof is preferably produced by coating and then firing. According to a preferred embodiment of the present invention, a coating solution containing a titanium alkoxide and a zirconium alkoxide as a precursor of titanium oxide and a precursor of zirconia is used and fired to obtain a photocatalyst layer.

In the present invention, as a precursor of titanium oxide, titanium alkoxide and chelated titanium can be suitably used. The titanium alkoxide is basically a substance represented by the general formula: Ti (OR) ₄ and is not limited as long as it generates photocatalytic titanium oxide by hydrolysis. A part of (OR) in the formula may be replaced with acetone (C ₅ H ₇ O ₂ ) or ethyl acetate (C ₆ H ₉ O ₃ ). According to a preferred embodiment of the present invention, the organic group R portion of the alkoxide (RO-) of the titanium alkoxide is a lower (preferably C _1-6 ) alkyl group. Preferred examples include tetraethyl titanate, tetraisopropyl titanate, tetra-n-propyl titanate, tetrabutyl titanate, tetramethyl titanate, and bis (ethylacetone) titanate. Diisopropyl ester, di (ethyl acetate) diisopropyl titanate, and mixtures thereof. Examples of the chelated titanium include titanium tetraacetamidine acetone.

In addition, as a precursor of zirconia, zirconium alkoxide and chelated zirconium can be suitably used. The zirconium alkoxide is basically a substance represented by the general formula: Zr (OR) ₄ and is not limited as long as zirconia is generated by hydrolysis. A part of (OR) in the formula may be replaced with acetone (C ₅ H ₇ O ₂ ) or ethyl acetate (C ₆ H ₉ O ₃ ). According to a preferred embodiment of the present invention, the organic group R portion of the alkoxide (RO-) of the zirconium alkoxide is a lower (preferably C _1-6 ) alkyl group. As specific examples thereof, tetraethyl zirconate, tetraisopropyl zirconate, tetrabutyl zirconate, monoethylacetonylacetone tributyl zirconate, and di (ethyl acetate) zirconate Butyl ester, bis (ethyl ethyl acetate) butyl ethylacetonyl acetonyl zirconate and mixtures thereof. Examples of the chelated zirconium include zirconium tetraacetamidine acetone.

The intermediate layer of the present invention can be suitably applied with a coating solution containing silicon dioxide, titanium oxide and / or zirconia, or a precursor thereof, and is preferably produced by coating and then firing. According to a preferred embodiment of the present invention, examples of the precursor of silicon dioxide include alkyl silicates such as methyl silicate and ethyl silicate, and polymers thereof. In addition, as the precursor of titanium oxide and the precursor of zirconia, those exemplified for the photocatalyst can be preferably used.

Examples of the solvent of the coating liquid include alcohols such as ethanol, isopropanol, and n-butanol, lyocells such as methylcellosolvin and butylcellosolvin, and aromatic hydrocarbons such as toluene and xylene. It is not particularly limited as long as it is a solvent in which titanium alkoxide and zirconium alkoxide are dissolved, or esters such as ethyl acetate and butyl acetate.

In the coating liquid, in addition to the above components, for example, a surfactant such as a leveling agent for improving the uniformity of the coating layer can be added.

The application of the coating liquid to the sanitary ware can be preferably performed by a generally widely used method such as brush coating, manual single roll coating, spray coating, roll coater, curtain coating, dip coating, flow coating, screen printing and the like.

The above-mentioned sanitary ware to which the coating liquid for forming the intermediate layer and the photocatalyst layer is applied has a firing step. The firing may be performed by an intermediate layer first, and then by a photocatalyst layer, but according to a preferred embodiment of the present invention, simultaneous firing is performed. The firing conditions can be appropriately determined, but for example, it is preferably performed at a temperature of 700 to 900 ° C for about 5 hours, and preferably at a temperature of 750 to 850 ° C. OK for 0.5 ~ 3 hours.

Based on the above, the preferred mode according to the present invention is clarified, and a method for manufacturing the sanitary pottery of the present invention is provided. This method is characterized in that it comprises coating a coating solution containing silicon alkoxide or its hydrolyzate and titanium alkoxide and / or zirconium alkoxide on the glaze layer of sanitary ware, and then coating a precursor containing titanium oxide. And a coating solution of a precursor of zirconia, and thereafter a step of firing at a temperature of 750 to 850 ° C.

[Example]

The present invention will be specifically described based on the following examples, but the present invention is not limited thereto.

Preparation of coating liquid for forming intermediate layer

Mix silanol (alkoxysilane hydrolysate, manufactured by Colcoat Co., Ltd.), and titanium alkoxide (di (ethylacetonyl) diisopropyl titanate NDH-510C, manufactured by Soda Co., Ltd.) or zirconyl alcohol Salt (compound name: monoethylammonium acetone tributyl zirconate trade name: ORGATIX ZC-540, manufactured by Matsumoto Fine Chemical Co., Ltd.) so that the weight ratio of the solid components after firing becomes the following table Documented ratio. Next, this mixture was diluted with a mixed solvent of 2-propanol (80%) and methyl lysin (20%) to give a solid content of 0.5% after firing, and the diluted solution was mixed with a stirrer. The obtained mixed liquid was allowed to stand for 1 hour or more, and this was used as a coating liquid for forming an intermediate layer.

Preparation of coating liquid for forming photocatalyst layer

Mixed with a titanium alkoxide (compound name: bis (ethylacetonyl) diisopropyl titanate) trade name: NDH-510C, manufactured by Soda Co., Ltd., and a zirconium alkoxide (compound name: monoacetamylacetone zirconium Tributyl acid trade name: ORGATIX ZC-540, manufactured by Matsumoto Fine Chemical Co., Ltd.) so that the weight ratio of the solid content of the titanium oxide / zirconia after firing becomes the ratio described in the following table. Next, this mixture was diluted with a mixed solvent of 2-propanol (80%) and methyl lysin (20%) to give a solid content of 0.5% after firing, and then the diluted solution was mixed with a stirrer. The obtained mixed liquid was allowed to stand for 1 hour or more, and this was used as a coating liquid.

Making of earthenware tiles

The pottery raw material was melt-casted to obtain a plain material, and the surface of the plain material was coated with a glaze using a manual spray gun (F100 Meiji Machinery Manufacturing Co., Ltd.). Next, while gradually raising and lowering the temperature, the tunnel kiln set at a maximum temperature of 1180 ° C was fired for 24 hours to obtain a ceramic tile. In addition, the glaze used the composition of the following range.

Glaze composition

Formation of intermediate layers

Using a manual spray gun (F100 Meiji Machinery Co., Ltd.) on the surface of the ceramic tile obtained from the above, the coating liquid for forming the intermediate layer obtained above was applied with a controlled amount so that the film thickness after firing became 50nm.

Formation and firing of photocatalyst layer

On the surface of the ceramic tile where the coating solution for forming the intermediate layer obtained above was applied, a manual spray gun (F100 Meiji Machinery Co., Ltd.) was used to control the coating amount and the coating solution for forming the photocatalyst layer was coated. So that the film thickness after firing becomes 50 nm.

Next, while gradually raising and lowering the temperature, firing was performed in a high-temperature electric furnace (manufactured by FUH732DA ADVANTEC Co., Ltd.) at a maximum temperature of 800 ° C for 24 hours to obtain a photocatalyst-coated tile.

Photocatalytic activity

The photocatalyst activity of photocatalyst-coated tiles is based on JIS (Japanese Industrial Standard) Quasi) R1703-2 as the benchmark, and evaluated based on the methylene blue decomposition index. The results were evaluated based on the following criteria.

Decomposition index is 7 or more: ○

5 or more and less than 7: △

Decomposition index is less than 5: ×

The results are shown in the following table.

Acid and alkali durability test

A test device was prepared in which acidic water (pH 3.5) and alkaline water (pH 9.5) alternately flowed out at a 2-minute interval for 10 seconds, and a photocatalyst-coated tile was installed under the running water of the device. At this time, both sides apply acidic water and alkaline water as a loop.

After a predetermined loop, a tape peeling test was performed based on JISK5600-5-6. The results were evaluated based on the following criteria.

Does not peel after 14000 cycles: ◎

Delamination occurred over 10,000 cycles and 14,000 cycles: ○

Delamination occurred after 6,000 cycles over 6,000 cycles: △

Stripping occurred up to 6000 times: ×

The results are shown in the following table.

Abrasion resistance test

A friction tester (manufactured by Taiping Rika Chemical Industry Co., Ltd.) was used to perform a friction resistance test on photocatalyst-coated tiles. Using a double-sided tape, the urethane sponge (scotchbright (SS-72K 3M Co., Ltd.)) After connecting the non-woven fabric to the friction surface, it was connected to the head, and then wetted with distilled water. Then, a 250 g load (load condition: 5 kPa) was rubbed for a predetermined number of times, and the presence or absence of surface damage was observed and confirmed. New urethane sponges are replaced every 1,000 rubs. The results were evaluated against the following benchmarks.

No visual damage after 20,000 rubs: ◎

Visible damage due to friction over 10,000 times and 20,000 times: ○

Visible damage due to friction over 2000 times 10,000 times: △

Visual damage due to friction up to 2000 times: ×

The results are shown in the following table.

In addition, the numerical value in a table | surface is a mass% or the value based on it.

Claims (9)

A sanitary pottery comprising a glaze layer, an intermediate layer provided on the glaze layer, and a photocatalyst layer provided on the intermediate layer, wherein the photocatalyst layer includes titanium oxide and zirconium oxide, and titanium oxide The content is 95% to 75% by mass, and the content of zirconia is 5 to 25% by mass. The intermediate layer includes silicon dioxide, and one or more selected from the group consisting of titanium oxide and zirconia, and the content of silicon dioxide It is 98% by mass to 85% by mass, and the total content of one or more kinds selected from the group consisting of titanium oxide and zirconia is 2% by mass to 15% by mass. For example, the sanitary ware of claim 1, wherein the aforementioned intermediate layer includes silicon dioxide and titanium oxide, the silicon dioxide content is 90 to 98% by mass, and the titanium oxide content is 2 to 10% by mass. The sanitary ware according to claim 2, wherein the content of the aforementioned silicon dioxide is 90 to 95% by mass, and the content of the aforementioned titanium oxide is 5 to 10% by mass. The sanitary ware according to claim 1, wherein the intermediate layer includes silicon dioxide and zirconia, the content of the silicon dioxide is 90 to 98% by mass, and the content of the zirconia is 2 to 10% by mass. The sanitary ware according to claim 4, wherein the content of the aforementioned silicon dioxide is 90 to 95% by mass, and the content of the aforementioned zirconia is 5 to 10% by mass. The sanitary ware according to any one of claims 1 to 5, wherein the titanium oxide content of the photocatalyst layer is 90 to 80% by mass, and the zirconia content is 10 to 20% by mass. The sanitary ware according to claim 1, wherein the intermediate layer has a film thickness of 50 to 150 nm. The sanitary ware according to claim 1, wherein the photocatalyst layer has a film thickness of 50 to 150 nm. A manufacturing method of sanitary ware, which is the manufacturing method of sanitary ware according to claim 1, comprising: coating and mixing a silicon alkoxide or a hydrolyzate thereof and a titanium alkoxide on a glaze layer of sanitary ware; and And / or a coating solution of a zirconium alkoxide, further coating a coating solution containing a precursor of titanium oxide and a precursor of zirconia, and then firing at a temperature of 750 to 850 ° C.